Filter



' Dec.v13, 19.32..` C, DAVlEs 1,890,499

FILTER Filed NOV. 25, 1931 Patented Dec. y13, 1932 CHARLES DAVIBS, OF NEW YORK, 'N'.gY.

FILTER.

Applicatonled November 25, 1931. Serial No. 577,177.

'Ihis invention relates to filters intendedl curved or bent in shape, the former suffers the inconvenience of complications 1n pack-V ing and shipping and the latter the difficulty of handling.

The main object of my invention therefore is to provide a flexible corrugated filter which shall have means' to retain the individual cori rugations in regular sequence.

Another object of my invention is to provide a filter which may be manufactured and packed in a standard manner and yet be adaptable to a wide range of conditions of use.

@ther and further objects and advantages will become apparent from the description below, in connection with the draw-ing, of a preferred embodimentof my invention. In the drawing:

Fig. 1 is a front elevational view of a filter insert according to my invention.

Fig. 2 is a detail in front elevation similar to Fig. 1 and showing a slight modification,

i parts being broken away to show the structure of the filter.

Fig. 3 is a side elevation of a part of Fig. 1, portions being broken away.

Fig. 4 is a view similar to Fig. 3 but show- 40 ing the filter bent or flexed as in use.

The filter embodying my invention also embodies preferably certain Vof the features shown in'my co-pending application for lters Serial No. 471,317 led July 28, 1930 and comprises a main ltering body 1 of fibrous material such as cellulose, supported and held between an entrance surface sheet 2 of sized, reticulated textile material or other similar semi-stiff reticulated mate- '50 rial, and an exit surface sheet of fuzzy `material of a textile nature. The assemblyl of cellulose and surface sheets is then pleated vor folded to form a spaced series of zlg-zags or corrugations 4. The ends of individual corrugations or folds are then crushed or mashed as at 5 to form flattened, spread end portions which overlap to provide a plane edge or rim 6 for the filter. The edges may then be stapled or stitched, and covered with felt strips; but preferably a strip of cloth, felt or other flexible inextensible material is folded over the edge as `at 7 and stitched thereto as in Fig. 1 at 8, or stapled thereto as in'Fig. 2 at 8. It is to be understood, of course, that the edging 7 lmay be secured to 35 the edge 6 in any other manner'withont de-4 parting from the principles of this invention. The ed ing 7 may be run around the four edges o the filter for convenience and simplicity of manufacture as shown in Fig. 1 but 70 it is clear that it may be replaced at what may be called the upper and lower edges 9 and l() by a relatively rigid strip of cardboard or other material.

In the preferred form of my invention,

which is shown in the drawing, it is to be noted that the ends ofthe ridges or folds on each side of the filter are fiattened to a line midway between the crests of the folds on one side and the crests of the folds on the other side; so that the fltersurface extends e ually on either side of the rim 6. The sprea flattened edges of successive folds on one side of the filter are overlapped, 'and the spread, flattenededges of successive folds on the other side of the filter are also overlapped. Thus the overlap of the edges of two consecutive folds on one side of the filter will come opposite the Continuous fiat edge portion that fold on the other side of the filter which corre- .90

sponds to the bottom half of the valley between `the crests of the two first-mentioned folds. f

The preferred embodiment shown in Fig. r, 1 is a unit with sufficient rigidity of form to 9" permit convenient handling. At the same time it may be easily bent or flexed about a horizontal axis as the conditions of use may req11ire. In such case the individual folds or corrugations will be held-in definite sequen- 10 opt tial relation by the lateral connectors or ties 7 which prevent the escape or wide separation of the said folds. For this last purpose the strips 7 may be replaced by strips of similar inextenszible flexible material attached to and running transversely of the corrugations and intermediate the lateral edges of the filter. However, the preferred form has animportantadvantage in most cases of actual use. By reducing the edge portion of the filter to a fiat surface or rim with a rectilinear edge the possibility of'air leakage about the edges of the filter is necessarily reduced; and the fit of the filter inside an aircasing or flue may be more easily made and need not be quite as exact'.

Having thus described 'my` invention, I claim:

I. A filter having a series of folds, each .mi ofthe said folds being spread at its ends, and

means to hold the spread ends in overlapping relation to form a flat rim for the filter.

2. A filter of fiexible material having a series of folds, the said folds being spread .25* at their ends to provide a flat, stralght rim and edge, for the filter, and a fiexible, inextensible strip secured to the ends of the folds to prevent the ends from separating during fiexure of the filter.

3. A filter of flexible material having a series of folds and flattened edges at the termination of the series, the said folds being spread at their ends to provide flattenedC lateral edges, and an edging of fiexible, inextensible material secured to the edges to preserve the fiat shape ofthe latter and to limit the relative change of position of the folds during flexure of the filter.

" f CHAS. DAVIES.Y 

